My research is mainly focused on distributed interactive applications, i.e., applications that allow multiple users to interact via the Internet independently of location and time. Important examples for such applications are shared whiteboards, distributed virtual environments, groupware systems, workspaces, software development tools for teams, and network computer games. These applications often have a replicated architecture which makes their development challenging: Each user runs a complete instance of the application so that all application data is replicated. Changes in that data then need to be distributed to all participating sites such that the local data copies are kept consistent. Besides these technical issues, the collaborative process among users needs to be supported.

More specifically, I am interested in

• Consistency control algorithms for keeping local copies of replicated data consistent.
• Late join algorithms to initialize new session members with the current shared state.
• Mechanisms that increase the awareness among participants and that support multi-user collaboration.
• Applications that allow interleaved synchronous and asynchronous collaboration.
• Realization of algorithms such that they are reusable for different applications.
• Application-level protocols for the transport of data.
• Protocols for efficient group communication, i.e., application-level and IP multicast.
• Overlay networks and peer-to-peer systems.
• Simulation analysis of network protocols and algorithms.
• User interfaces and the impact of the aforementioned mechanisms on the user.